Electrical stimulation achieves neuromodulation by controlling the release of neurotransmitters in specific parts of the nervous system through induction of action potentials. Electrical stimulation involves transduction of electrical current from the device to ionic current in the nervous tissue. Extracellular methods have been developed to pass current into the tissue, affecting the extracellular voltage potential of the neuronal membrane. These methods typically utilize an implanted neurostimulator to deliver the electrical current.
Implanted electrical neurostimulators draw power from a finite energy supply (e.g., a battery), requiring either frequent recharge cycles or surgical replacement upon full discharge. Accordingly, batteries for conventional electrical neurostimulators must be sufficiently large to meet existing power requirements, which typically results in increased volume for implantable systems.